1. Field
The invention is in the field of devices for applying electrical signals to a living body and to methods of treating body conditions and producing reactions and conditions in living bodies by means of applying electrical signals to such bodies.
2. State of the Art
There are currently various kinds of electric stimulators and methods of applying electrical signals to a body available for the purpose of managing pain and its associated stress, stimulating muscle function, and for treating various medical and other body conditions and/or the symptoms thereof. The stimulators and methods of the prior art are usually referred to in catagories recognized by the acronyms: TENS (Transcutaneous Electrical Nerve Stimulation), MENS (Microvolt Electrical Nerve Stimulation), and EMS (Electric Muscle Stimulation).
When the application of electrical signals are directed to the treatment of pain, the equipment and methods used are usually referred to as TENS (Transcutaneous Electrical Nerve Stimulation) systems. It is claimed that such systems are able to stimulate specific nerves to ease pain at a specific point in a body.
There are two major theories explaining how electric stimulation relieves pain. According to the first theory, thexe2x80x94xe2x80x9cgate control theory,xe2x80x9dxe2x80x94pain and non-pain impulses are sent to the brain from the local nervous system. These pulses travel through the cutaneous (surface nerves) to the afferent (deeper) nerves and then to the spinal cord and brain. Along the path are many areas referred to as xe2x80x9cgates.xe2x80x9d These gates determine which impulses are allowed to continue to the brain and thus prevent the brain from receiving too much information too quickly. Also, since a single nerve cannot carry a pain impulse and a non-pain impulse simultaneously, it is said that the stronger, non-pain impulse from the TENS device xe2x80x9ccontrols the gatexe2x80x9d and keeps the body form feeling the pain.
According to the second theory, TENS stimulation encourages the body to produce natural pain killing chemicals called endorphins. These chemicals are said to interact with neuron receptors in such a way as to block the perception of pain. The effect is much the same as that of the pharmaceutical drug morphine but without the side effects associated with use of the drug.
TENS units use carbon rubber electrodes that can be affixed to the skin in various ways, such as with adhesive tape. These electrodes deliver bursts of electrical current through the coetaneous surface skin in contact with the electrodes to the afferent (deep) nerves for the purpose of controlling pain. However, since these electrodes have direct contact with the skin there is an inherent problem. Direct contact between the electrodes and the skin can induce paresthesia, (a tingling sensation) that can cause feelings of heat or burningxe2x80x94even the point of feeling like being electrocuted. These and other forms of discomfort are present depending upon the current flowing from the electrodes into the skin. The current flow depends upon the strength of the signal applied to the electrodes and the power contained in the signals. Thus, unless the current is delivered at very low level, the experience can become very uncomfortable and at times extremely painful and stressful. The amount of power that can be applied to a body through electrodes in direct contact with the skin of the body is generally in the range of about ten to twelve watts. Power levels above that cause to much current flow from the electrodes into the skin in contact with the electrodes and are painful.
Another problem with prior art TENS devices are that they deliver a bipolar waveform that is not truly compatible with the digital, polar signals produced by the human and other living bodies.
MENS (Microvolt Electrical Nerve Stimulation) devices have been described for use as electro acupuncture devices. MENS devices deliver an electric pulse approximately three orders of magnitude less than a TENS device. With lesser voltage and wattage, the signal is less likely to burn. Also, the MENS signal, when delivered through the acupuncture points, tends to be more xe2x80x9cphysiologicxe2x80x9d in that it mimics the body""s electric signals. Those who are skilled in the art are now tending to believe that physiological compatibility is important.
With the MENS systems, however, the needles form direct electrodes in contact with tissue. Thus, this combination of the needles and the electric current can still become more of a torture than a treatment. It can be very uncomfortable depending on the voltage used to drive the signal. In fact, since the needles create much smaller electrodes than the electrodes generally placed on the skin, much smaller signal are necessary to avoid discomfort. Another concern is that the prior art MENS devices actually deliver a bipolar waveform that is not truly compatible with the digital, polar human body. In addition, a skilled acupuncturist is necessary to place the needles, thus making it impossible for a user to use the device his or her own.
EMS (Electric Muscle Stimulation) uses electro stimulation to sooth muscle aches and pains, provide electro muscle massage, and to tone muscles and build muscle mass. Normal neurological control of muscle contraction (tetanus) is accomplished with positive electrical signals produced by the body. EMS provides a mechanism and the means for causing contraction of muscles using an external stimulus (artificial tetanus). However, prior art EMS (Electric Muscle Stimulation) teaches the use of bipolar waveforms. In addition, electrodes are used which again limit the amount of current and power that can be applied to the body.
Many of the prior art TENS, MENS, and EMS devices allow the operator to vary the frequency and intensity of the signal applied to the body during a treatment session. Some of the prior art devices even automatically vary the frequency and intensity of the signal as part of the treatment. This appears to cause confusion within the body when it has to constantly adapt from one signal to another and does not appear to be beneficial.
According to the invention, electrical signals can be introduced into the body using applicators that generate a current flow in the body but do not cause current to flow directly from the applicator into the body. This allows higher levels of power to be applied to the body without the burning and feelings of electrocution that accompany high power levels using conventional electrodes where current flows directly from the electrode through the skin into the body. The applicators of the invention include electrically conductive material covered by electrically insulating material which contacts the body to prevent direct body contact with the electrically conductive material. It has been found that a length of multiconductor flat or ribbon cable such as used in internal computer connections between circuit boards or cards works very well. Each of the individual conductors or wires in the cable appears to form an antenna for transmitting power into the body, and is more efficient than a single conductive plate. Preferred applicators are relatively large with surface areas of up to about 120 square centimeters. Power densities of up to about one watt per square centimeter can be used with no discomfort to the recipient. This means that with a 120 square centimeter applicator surface, up to about 120 watts of power can be comfortably applied to the body. It has been found that the intensity of the signal applied to the body is important. Higher intensity signals appear to provide better therapeutic results, although it is usually preferred to build up to the higher intensity signals.
A further significant aspect of the invention is the use of positive pulses to cause generation of the electrical signals in the body rather than bipolar (AC) signals. The natural neurological signals in the body are positive signals, not AC signals. Therefore, using positive signals rather than AC signals more closely mimic the natural body signals and creates signals within the body that are more compatible with and accepted by the body than AC signals. While pulse frequencies from about 1 to 10,000 hertz can be used, pulse frequencies in the range of about 40 to 100 hertz have been found preferable. Frequencies below about 40 hertz tend to make a person sleepy while frequencies above about 100 hertz tend to make a person feel somewhat on edge or uncomfortable. It is preferred that the pulse width be between about 0.5 and 1 millisecond, and the signals may range in voltages up to about 20,000 volts. Power applied may range up to about 120 watts
The electrical stimulation device of the invention can be used wherever prior art electrical stimulation devices are used and generally with the increased power of the signals generated and the purely positive pulses used, have been found to be more effective in such uses than the prior art devices. The stimulator of the invention can be used very effectively for the treatment of pain and related stress, such as from headaches, arthritis, injuries such as back injuries, carpal tunnel syndrome, or other causes, and has been found to help in the healing of such conditions. It can be used for muscle stimulation for muscle development and rehabilitation. It has been found that it can be used for finding and identifying microorganisms within a body where once the organisms have been identified, they are attacked by and destroyed by the body""s own immune system. It has also been found that use of the device can slow or prevent bleeding and bruising, can break down blood clots, and is effective in reversing skin damage from sun exposure.